1. Field of the Invention
The present invention relates to an aqueous ink composition for inkjet recording and an image forming method.
2. Description of the Related Art
Pigment-based inks are available as inks for inkjet printers. Pigments are superior to dyes in light resistance and water resistance, and in recent years, pigments have been used as the colorants for ink compositions for inkjet printers, for the purpose of improving light resistance and water resistance. However, since pigments are generally insoluble in water, when a pigment is to be used in a water-based ink composition, it is necessary to mix the pigment with a dispersant such as a water-soluble resin and stably disperse the pigment in water prior to the preparation of the ink composition.
In order to stably disperse a pigment in a water-based system, it is needed to examine the type and the particle diameter of the pigment, the type of the resin used, the dispersing means and the like, and various dispersing methods and ink compositions for inkjet recording have been suggested thus far.
For example, there is disclosed an ink composition containing a polyester resin as an essential component, which has good storage stability of ink and excellent image glossiness (see, for example, Japanese Patent No. 417-4666).
However, the ink composition described in Japanese Patent No. 417-4666 does not have satisfactory jettability after long-term storage or high-temperature storage of the ink composition.